1. Field of the Invention
The present invention relates to a pump-oxygenator system which, during open heart surgery, has both cardiac pump function and pulmonary gas exchange function on the outside of a patient, and sucks and collects blood prevailing in the site being operated, etc., for recycling purposes
2. Prior Art
Leading functions of a pump-oxygenator are to store a pool of blood drawn from a patient in a reservoir, and use a roller pump to feed the blood stored in the reservoir into a heat exchanger or other suitable temperature regulation means where the blood is kept at a suitable temperature, and whence the blood is delivered to the patient upon subjected to gas exchange in artificial lungs.
Upon open heart surgery being performed, blood is emitted in the site being operated while some amounts of bloods stagnate in the pericardium, the heart, the main artery, etc. The blood emitted in the site being operated as well as the blood stagnating in the pericardium, the heart, the main artery, etc. are discarded at an initial stage of open heart surgery without being recycled.
In recent years, however, the blood emitted in the site being operated as well as the blood stagnating in the pericardium, the heart, the main artery, etc. have been capable of being collected in a reservoir for re-delivery to the patient using a roller pump, primarily because the roller pump used has improved performance.
However, much difficulty is involved in making a compact pump-oxygenator assembly including one or more sub-roller pumps in addition to the blood delivery roller pump. Thus, it is required to locate one or more such sub-roller pumps at positions spaced away from the patient; that is, the area occupied by the pump-oxygenator assembly in an operating room is unavoidably increased. This results in the following disadvantage:
a) The pump-oxygenator assembly has a possibility of interfering with operations by an operator who performs open heart surgery as well as assistants and, hence, obstructing smooth operations. PA1 b) The overall length of tubes through which blood flows is increased, resulting in an increase in the amount of an electrolyte and other solution filled in the system, and so some considerable burdens being imposed on the patient. PA1 c) With the area occupied by the pump-oxygenator assembly becoming large, it is awkward for an operator who manipulates the pump-oxygenator assembly to maintain careful yet overall inspection over it. PA1 d) The pump-oxygenator assembly costs a lot. PA1 (a) a main reservoir capable of storing a pool of blood supplied from a blood-drawing line and guiding the stored blood to a blood delivery line, PA1 (b) a pump located in said blood delivery line for supplying the blood stored in said main reservoir, PA1 (c) artificial lungs located in said blood delivery line for adding oxygen to a blood stream flowing through said blood delivery line and removing carbonic acid gas therefrom, PA1 (d) a plurality of sub-reservoirs located upstream of said main reservoir to store blood therein, PA1 (e) a plurality of sub-suction lines for blood, which are respectively connected to said plurality of sub-reservoirs, PA1 (f) a guidance means for guiding the bloods supplied into said plurality of sub-reservoirs to said main reservoir, and PA1 (g) a controller for independently subjecting interiors of said plurality of sub-reservoirs to negative pressure control. PA1 (i) Open heart surgery can be performed easily and smoothly, because the pump-oxygenator has little, if any, possibility of interfering with operations by both an operator and assistants. PA1 (ii) The overall length of tubes through which blood flows can be so reduced that the amount of an electrolyte or other solution filled in the system can be reduced than ever before, thereby retrieving burdens on the patient. PA1 (iii) The pump-oxygenator can be readily manipulated due to its size reduction, because the operator can maintain easy yet overall inspection thereover.
Another conventional pump-oxygenator uses roller pumps for a blood delivery main pump and a suction sub-pump. The roller pump needs long preliminary periods prior to performing open heart surgery because of the need of conducting preliminary test-runs such as appropriate pressure closing tests for inspecting the engagement of rollers with tubes, and functionality tests. For this reason, it is unfeasible to perform quick operations in an emergency case.
Furthermore, the roller pump causes some damage to blood because the rollers have action on compressing blood in the tubes, and because it applies excessive loads on blood due to its mechanical driving.
Situations being like this, it is therefore an object of the present invention to provide a pump-oxygenator system which can not only be used with so great safety that burdens on a patient can be relieved but also readily manipulated with careful yet overall inspection maintained over it, and can be made compact at low cost.